ECMA-334: 14.2.3 Unary operator overload resolution

C# Language Specification

14. Expressions 14.2 Operators 14.2.1 Operator precedence and associativity 14.2.2 Operator overloading 14.2.3 Unary operator overload resolution 14.2.4 Binary operator overload resolution 14.2.5 Candidate user-defined operators 14.2.6 Numeric promotions 14.2.7 Lifted operators

© 2006 ECMA International

14.2.3 Unary operator overload resolution

An operation of the form op x or x op, where op is an overloadable unary operator, and x is an expression of type X, is processed as follows:

• The set of candidate user-defined operators provided by X for the operation operator op(x) is determined using the rules of §14.2.5.

• If the set of candidate user-defined operators is not empty, then this becomes the set of candidate operators for the operation. Otherwise, the predefined unary operator op implementations become the set of candidate operators for the operation. If type X is not an enum type, then any predefined unary operator with a parameter type that is an enum type is removed from consideration. The predefined implementations of a given operator are specified in the description of the operator (§14.5 and §14.5.14).

• The overload resolution rules of §14.4.2 are applied to the set of candidate operators to select the best operator with respect to the argument list (x), and this operator becomes the result of the overload resolution process. If overload resolution fails to select a single best operator, a compile-time error occurs.